Method for transmitting and receiving data in wireless communication system, and device for supporting same

ABSTRACT

The present invention relates to a method and a device for transmitting and receiving data by a terminal in a wireless communication system. The present invention can provide a method and a device configured to: generate at least one duplicated data according to the number of multiple radio bearers by using specific data in a first layer of a transmitting device; transmit the specific data and the at least one duplicated data to a receiving device on multiple cells associated with the multiple radio bearers; and when receiving, from the receiving device, an ACK indicating the success of reception of the specific data and the at least one duplicated data, instruct to stop transmission of the specific data and the at least one duplicated data from the first layer to a second layer, wherein the multiple radio bearers are instructed, by a bearer identifier, to transmit the duplicated data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2017/004588, filed on Apr. 28, 2017,which claims the benefit of U.S. Provisional Application No. 62/330,857,filed on May 3, 2016, and 62/334,465, filed on May 11, 2016, thecontents of which are all hereby incorporated by reference herein intheir entirety.

TECHNICAL FIELD

The present invention relates to a method for a user equipment totransmit and receive data in a wireless communication system and, moreparticularly, to a method of improving reliability of data transmissionand reception and an apparatus supporting the same.

BACKGROUND ART

Mobile communication systems have emerged to provide a voice servicewhile guaranteeing mobility of a user. The mobile communication systemof today has been expanded to support data services in addition to thevoice service. Due to the explosive increase of today's traffic,resources are running short; more and more users are demanding higherspeed services; and a more advanced mobile communication system isrequired accordingly.

Key requirements for a next-generation mobile communication systeminclude accommodation of explosive data traffic, significant increase oftransmission rate per user, accommodation of a significantly increasednumber of connected devices, very low end-to-end latency, and highenergy efficiency. In order to meet the requirements, varioustechnologies such as dual connectivity, massive Multiple Input MultipleOutput (MIMO), in-band full duplex, Non-Orthogonal Multiple Access(NOMA), super wideband, and device networking are being studied.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method and a devicefor redundantly transmitting the same data so as to increase reliabilityof data transmission.

Another object of the present invention is to provide a method and adevice for transmitting the same data via multiple component carriers(CCs) to which carrier aggregation (CA) is applied.

Another object of the present invention is to provide a method and adevice for generating duplicate data through replication of data at aspecific layer of a transmitting device.

Another object of the present invention is to provide a method and adevice for defining an operation of each layer of a user equipment so asto transmit duplicated multiple same data through a plurality of logicalpaths.

Another object of the present invention is to provide a method and adevice for configuring a separate identifier (ID) so as to identify alogical path for transmitting duplicate data.

Another object of the present invention is to provide a method and adevice for processing duplicate data in a receiving device whenreceiving the duplicate data.

Another object of the present invention is to provide a method and adevice for recovering data received by a receiving device when receivingduplicate data.

Technical problems to be solved by the present invention are not limitedby the above-mentioned technical problems, and other technical problemswhich are not mentioned above can be clearly understood from thefollowing description by those skilled in the art to which the presentinvention pertains.

Technical Solution

In order to solve the above-described and other problems, the presentinvention provides a method and a device for transmitting and receivingdata in a wireless communication system.

More specifically, a method for transmitting and receiving dataaccording to one embodiment of the present invention comprisesgenerating at least one duplicate data according to a number of aplurality of radio bearers using specific data at a first layer of atransmitting device; transmitting the specific data and the at least oneduplicate data to a receiving device on a plurality of cells associatedwith the plurality of radio bearers; and when receiving Ack indicating areception success of the specific data and the at least one duplicatedata from the receiving device, instructing a stop of transmission ofthe specific data and the at least one duplicate data from the firstlayer to a second layer, wherein in the plurality of radio bearers, atransmission of duplicate data is indicated by a bearer identifier.

In the present invention, the first layer performs a header compressionfunction.

In the present invention, the specific data and the at least oneduplicate data are reconfigured by the second layer.

In the present invention, the method further comprises delivering thespecific data from a TCP/IP layer of the transmitting device to thefirst layer; and storing the specific data in a first transmissionbuffer of the first layer.

In the present invention, a number of the second layers is equal to anumber of the specific data and the at least one duplicate data.

In the present invention, the specific data and the at least oneduplicate data are reconfigured through a segmentation and concatenationfunction based on an allocated resource.

In the present invention, the allocated resource is determined by radioconditions, a transmission power, a transmission resource, or quality ofservice (QoS) of each of the plurality of radio bearers.

The present invention provides a method comprising receiving specificdata and at least one duplicate data from a transmitting device on aplurality of cells associated with a plurality of radio bearers;delivering the specific data and the at least one duplicate data from afirst layer of a receiving device to a second layer of the receivingdevice; storing one data among the specific data and the at least oneduplicate data in a reception buffer of the second layer; and discardingremaining data excluding the one data from the specific data and the atleast one duplicate data.

The method further comprises instructing a stop of transmission of dataduplicated with the one data from the second layer to the first layer.

The method further comprises performing a radio link control functionbased on the specific data and the at least one duplicate data throughthe first layer. The radio link control function is one of a hybridautomatic repeat request (HARQ) function, a reassembly function ofsegmented or concatenated data, or a recovery function of lost data.

The method further comprises recovering the one data through the secondlayer; and delivering the recovered one data to a TCP/IP layer.

The method further comprises transmitting, to the transmitting device,Ack indicating a reception success of the specific data or the at leastone duplicate data.

The present invention provides a transmitting device comprising acommunication unit configured to transmit and receive a radio signalwith an outside; and a processor functionally coupled to thecommunication unit, wherein the processor is configured to generate atleast one duplicate data according to a number of a plurality of radiobearers using specific data at a first layer of the transmitting device,transmit the specific data and the at least one duplicate data to thereceiving device on a plurality of cells associated with the pluralityof radio bearers, and when receiving Ack indicating a reception successof the specific data and the at least one duplicate data from thereceiving device, request a stop of transmission of the specific dataand the at least one duplicate data from the first layer to a secondlayer, wherein in the plurality of radio bearers, a transmission ofduplicate data is indicated by a bearer identifier.

Advantageous Effects

The present invention has an effect capable of increasing reliability ofdata transmission by transmitting the same data via multiple componentcarriers (CCs) to which carrier aggregation (CA) is applied, or multiplecells to which dual connectivity is applied.

The present invention has an effect capable of redundantly transmittingthe same data by configuring or reconfiguring a logical path.

The present invention has an effect that a UE can identify a logicalpath through which duplicate data is transmitted by configuring aseparate identifier (ID) so as to identify a logical path for thetransmission of duplicate data.

The present invention has an effect that when the same uplink data isredundantly transmitted, a base station can identify whether or not theduplicated uplink data is transmitted by transmitting an indication orindex information informing of the uplink data transmission via controlinformation.

The present invention has an effect capable of generating multiple samedata for providing the same service by generating duplicate data throughreplication of data in a specific layer of a transmitting device.

The present invention has an effect capable of transmitting multiplesame data on one or more component carriers by individuallyreconfiguring the multiple same data because specific layers forreconfiguring generated multiple data according to allocated resourcesare present as many as the number of multiple data.

The present invention has an effect capable of efficiently processingtransmitted multiple same data by discarding remaining data excludingone data from multiple same data received by a receiving device whenreceiving the multiple same data.

The present invention has an effect that when one of multiple same datais successfully received, resource waste resulting from the redundanttransmission of multiple same data can be reduced by transmitting aresponse message to the successful reception and stopping thetransmission of the multiple same data.

Effects obtainable from the present invention are not limited by theabove-mentioned effect, and other effects which are not mentioned abovecan be clearly understood from the following description by thoseskilled in the art to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included herein as a part of adescription in order to help understanding of the present invention,provide embodiments of the present invention, and describe the technicalfeatures of the present invention with the description below.

FIG. 1 illustrates an Evolved Packet System which is associated with theLong Term Evolution (LTE) system to which the present invention can beapplied.

FIG. 2 is a block diagram illustrating an example of a radio protocolarchitecture to which technical features of the present invention areapplicable.

FIG. 3 is a flowchart illustrating a process of establishing an RRCconnection to which the present invention is applicable.

FIG. 4 is a flowchart illustrating an RRC connection reconfigurationprocess to which the present invention is applicable.

FIGS. 5 and 6 are diagrams showing examples of Layer 2 structures incarrier aggregations to which the present invention is applicable.

FIG. 7 is a diagram showing an example of component carriers and carrieraggregations in a wireless communication system to which the presentinvention is applicable.

FIGS. 8 and 9 illustrate an example of a structure of dual connectivityand a network interface to which the present invention is applicable.

FIG. 10 is a flow chart illustrating an example of a method fortransmitting the same data proposed by the present specification.

FIGS. 11 to 13 illustrate an example of a multiplexing method fortransmitting the same data proposed by the present specification.

FIGS. 14 and 15 illustrate an example of a method and a de-multiplexingmethod for receiving and processing the same data proposed by thepresent specification.

FIG. 16 illustrates an example of an internal block diagram of awireless device to which the present invention is applicable.

MODE FOR INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description set forth below in connection withthe appended drawings is a description of exemplary embodiments and isnot intended to represent the only embodiments through which theconcepts explained in these embodiments can be practiced. The detaileddescription includes details for the purpose of providing anunderstanding of the present invention. However, it will be apparent tothose skilled in the art that these teachings may be implemented andpracticed without these specific details.

In some instances, known structures and devices are omitted, or areshown in block diagram form focusing on important features of thestructures and devices, so as not to obscure the concept of the presentinvention.

In the embodiments of the present invention, the enhanced Node B (eNodeB or eNB) may be a terminal node of a network, which directlycommunicates with the terminal. In some cases, a specific operationdescribed as performed by the eNB may be performed by an upper node ofthe eNB. Namely, it is apparent that, in a network comprised of aplurality of network nodes including an eNB, various operationsperformed for communication with a terminal may be performed by the eNB,or network nodes other than the eNB. The term “eNB” may be replaced withthe term “fixed station”, “base station (BS)”, “Node B”, “basetransceiver system (BTS),”, “access point (AP)”, “MeNB (Macro eNB)”,“SeNB (Secondary eNB)” etc. The term “user equipment (UE)” may bereplaced with the term “terminal”, “mobile station (MS)”, “user terminal(UT)”, “mobile subscriber station (MSS)”, “subscriber station (SS)”,“Advanced Mobile Station (AMS)”, “Wireless terminal (WT)”, “Machine-TypeCommunication (MTC) device”, “Machine-to-Machine (M2M) device”,“Device-to-Device (D2D) device”, wireless device, etc.

In the embodiments of the present invention, “downlink (DL)” refers tocommunication from the eNB to the UE, and “uplink (UL)” refers tocommunication from the UE to the eNB. In the downlink, transmitter maybe a part of eNB, and receiver may be part of UE. In the uplink,transmitter may be a part of UE, and receiver may be part of eNB.

Specific terms used for the embodiments of the present invention areprovided to aid in understanding of the present invention. Thesespecific terms may be replaced with other terms within the scope andspirit of the present invention.

The embodiments of the present invention can be supported by standarddocuments disclosed for at least one of wireless access systems,Institute of Electrical and Electronics Engineers (IEEE) 802, 3rdGeneration Partnership Project (3GPP), 3GPP Long Term Evolution (3GPPLTE), LTE-Advanced (LTE-A), and 3GPP2. Steps or parts that are notdescribed to clarify the technical features of the present invention canbe supported by those documents. Further, all terms as set forth hereincan be explained by the standard documents.

Techniques described herein can be used in various wireless accesssystems such as Code Division Multiple Access (CDMA), Frequency DivisionMultiple Access (FDMA), Time Division Multiple Access (TDMA), OrthogonalFrequency Division Multiple Access (OFDMA), Single Carrier-FrequencyDivision Multiple Access (SC-FDMA), “non-orthogonal multiple access(NOMA)”, etc. CDMA may be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA may be implemented as a radiotechnology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Evolved-UTRA (E-UTRA) etc. UTRA is a part of Universal MobileTelecommunication System (UMTS). 3GPP LTE is a part of Evolved UMTS(E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA for downlink and SC-FDMAfor uplink. LTE-A is an evolution of 3GPP LTE.

Embodiments of the present invention may be supported by the standarddocuments disclosed in at least one of IEEE 802, 3GPP and 3GPP2 that areradio access systems. That is, steps or portions not described so thatthe technical spirit of the present invention is not clearly exposed inthe embodiments of the present invention may be supported by thedocuments. Furthermore, all terms disclosed in this document may bedescribed by the standard documents.

In order to clarify the description, 3GPP LTE/LTE-A is basicallydescribed, but the technical characteristic of the present invention isnot limited thereto and may be applied to a 5G system.

Prior to a description given with reference to the drawings, in order tohelp understanding of the present invention, terms used in thisspecification are defined in brief.

EPS: an abbreviation of an evolved packet system, and the EPS means acore network supporting a long term evolution (LTE) network. It is anetwork of a form in which an UMTS has been evolved

Public data network (PDN): an independent network where a serverproviding services is located

Access point name (APN): It is provided to a UE in the name of an accesspoint managed by a network. That is, this indicates the name (textstring) of a PDN. A corresponding PDN for the transmission and receptionof data is determined based on the name of an access point.

Tunnel endpoint identifier (TEID): an end point ID of a tunnelconfigured between nodes within a network, and the TEID is configuredfor each section in a bearer unit of each UE.

MME: an abbreviation of a mobility management entity, and the MMEfunctions to control each entity within an EPS in order to provide asession and mobility for a UE.

Session: a session is a passage for data transmission, and a unitthereof may be a PDN, a bearer or an IP flow unit.

A difference between units may be divided into a target network entireunit (APN or PDN unit), a unit (bearer unit) classified as QoS therein,and a destination IP address unit as defined in 3GPP.

EPS Bearer: a logical path generated between a UE and a gateway, inwhich a variety of types of traffic is transmitted and received.

Default EPS bear: a logical path for data transmission and receptionbasically generated when a UE accesses a network and can be maintaineduntil the UE is detached from the network.

Dedicated EPS bearer: a logical path generated when it is necessary toadditionally provide services after a default EPS bearer is generated.

IP flow: a variety of types of traffic transmitted and received througha logical path between a UE and a gateway.

Service data flow (SDF): a combination of IP flows of user traffic ormultiple IP flows classified depending on a service type.

PDN connection: this indicates a connection from a UE to a PDN, that is,association (connection) between a UE represented as an ip address and aPDN represented as an APN. This means a connection (UE-PDN GW) betweenentities within a core network so that a session can be formed.

UE Context: context information of a UE used to manage a UE in anetwork, that is, context information including a UE id, mobility(current location), and the attributes (QoS, priority) of a session

FIG. 1 is a view illustrating an Evolved Packet System which isassociated with the Long Term Evolution (LTE) system to which thepresent invention may apply.

The LTE system aims to provide seamless Internet Protocol (IP)connectivity between a user equipment (UE) and a pack data network(PDN), without any disruption to the end user's application duringmobility. While the LTE system encompasses the evolution of the radioaccess through an E-UTRAN (Evolved Universal Terrestrial Radio AccessNetwork) which defines a radio protocol architecture between a userequipment and a base station, it is accompanied by an evolution of thenon-radio aspects under the term ‘System Architecture Evolution’ (SAE)which includes an Evolved Packet Core (EPC) network. The LTE and SAEcomprise the Evolved Packet System (EPS).

The EPS uses the concept of EPS bearers to route IP traffic from agateway in the PDN to the UE. A bearer is an IP packet flow with aspecific Quality of Service (QoS) between the gateway and the UE. TheE-UTRAN and EPC together set up and release the bearers as required byapplications.

The EPC, which is also referred to as the core network (CN), controlsthe UE and manages establishment of the bearers.

As depicted in FIG. 1, the node (logical or physical) of the EPC in theSAE includes a Mobility Management Entity (MME) 30, a PDN gateway(PDN-GW or P-GW) 50, a Serving Gateway (S-GW) 40, a Policy and ChargingRules Function (PCRF) 60, a Home subscriber Server (HSS) 70, etc.

The MME 30 is the control node which processes the signaling between theUE and the CN. The protocols running between the UE and the CN are knownas the Non-Access Stratum (NAS) protocols. Examples of functionssupported by the MME 30 includes functions related to bearer management,which includes the establishment, maintenance and release of the bearersand is handled by the session management layer in the NAS protocol, andfunctions related to connection management, which includes theestablishment of the connection and security between the network and UE,and is handled by the connection or mobility management layer in the NASprotocol layer.

The S-GW 40 serves as the local mobility anchor for the data bearerswhen the UE moves between eNodeBs. All user IP packets are transferredthrough the S-GW 40. The S-GW 40 also retains information about thebearers when the UE is in idle state (known as ECM-IDLE) and temporarilybuffers downlink data while the MME initiates paging of the UE tore-establish the bearers. Further, it also serves as the mobility anchorfor inter-working with other 3GPP technologies such as GPRS (GeneralPacket Radio Service) and UMTS (Universal Mobile TelecommunicationsSystem).

The P-GW 50 serves to perform IP address allocation for the UE, as wellas QoS enforcement and flow-based charging according to rules from thePCRF 60. The P-GW 50 performs QoS enforcement for Guaranteed Bit Rate(GBR) bearers. It also serves as the mobility anchor for inter-workingwith non-3GPP technologies such as CDMA2000 and WiMAX networks.

The PCRF 60 serves to perform policy control decision-making, as well asfor controlling the flow-based charging functionalities.

The HSS 70, which is also referred to as a Home Location Register (HLR),contains users' SAE subscription data such as the EPS-subscribed QoSprofile and any access restrictions for roaming. Further, it also holdsinformation about the PDNs to which the user can connect. This can be inthe form of an Access Point Name (APN), which is a label according toDNS (Domain Name system) naming conventions describing the access pointto the PDN, or a PDN Address which indicates subscribed IP addresses.

Between the EPS network elements shown in FIG. 1, various interfacessuch as an S1-U, S1-MME, S5/S8, S11, S6a, Gx, Rx and SGi are defined.

Hereinafter, the concept of mobility management (MM) and a mobilitymanagement (MM) back-off timer is explained in detail. The mobilitymanagement is a procedure to reduce the overhead in the E-UTRAN andprocessing in the UE.

When the mobility management is performed, all UE-related information inthe access network can be released during periods of data inactivity.This state can be referred to as EPS Connection Management IDLE(ECM-IDLE). The MME retains the UE context and the information about theestablished bearers during the idle periods.

To allow the network to contact a UE in the ECM-IDLE, the UE updates thenetwork as to its new location whenever it moves out of its currentTracking Area (TA). This procedure is called a ‘Tracking Area Update’,and a similar procedure is also defined in a universal terrestrial radioaccess network (UTRAN) or GSM EDGE Radio Access Network (GERAN) systemand is called a ‘Routing Area Update’. The MME serves to keep track ofthe user location while the UE is in the ECM-IDLE state.

When there is a need to deliver downlink data to the UE in the ECM-IDLEstate, the MME transmits the paging message to all base stations (i.e.,eNodeBs) in its current tracking area (TA).

Thereafter, eNBs start to page the UE over the radio interface. Onreceipt of a paging message, the UE performs a certain procedure whichresults in changing the UE to ECM-CONNECTED state. This procedure iscalled a ‘Service Request Procedure’. UE-related information is therebycreated in the E-UTRAN, and the bearers are re-established. The MME isresponsible for the re-establishment of the radio bearers and updatingthe UE context in the eNodeB.

When the above-explained mobility management (MM) is applied, a mobilitymanagement (MM) back-off timer can be further used. In particular, theUE may transmit a Tracking Area Update (TAU) to update the TA, and theMME may reject the TAU request due to core network congestion, with atime value associated with the MM back-off timer. Upon receipt of thetime value, the UE may activate the MM back-off timer.

FIG. 2 is a block diagram illustrating an example of a radio protocolarchitecture to which technical features of the present invention areapplicable.

In FIG. 2, (a) is a block diagram illustrating an example of a radioprotocol architecture for a user plane, and (b) is a block diagramillustrating an example of a radio protocol architecture for a controlplane.

The user plane is a protocol stack for user data transmission, and thecontrol plane is a protocol stack for a control signal transmission.

Referring to (a) and (b) of FIG. 2, a physical (PHY) layer providesinformation transfer services to an upper layer using a physicalchannel. The PHY layer is connected to a medium access control (MAC)layer, that is an upper layer, through a transport channel. Data movesbetween the MAC layer and the PHY layer through the transport channel.The transport channel is classified according to how and which featuredata is transmitted via a radio interface.

Data moves between different PHY layers, i.e., between a PHY layer of atransmitter and a PHY layer of a receiver through a physical channel.The physical channel may be modified in an orthogonal frequency divisionmultiplexing (OFDM) scheme and utilizes a time and a frequency as radioresources.

Functions of the MAC layer include mapping between a logical channel anda transport channel and multiplexing/demultiplexing of a MAC servicedata unit (SDU) belonging to the logical channel to a transport blockprovided to the physical channel on the transport channel, where themeaning of ‘/’ includes both concepts of ‘or’ and ‘and’. The MAC layerprovides services to a radio link control (RLC) layer through thelogical channel.

Functions of the RLC layer include concatenation, segmentation, andreassembly of a RLC SDU. In order to ensure various quality of services(QoS) demanded by a radio bearer (RB), the RLC layer provides threeoperation modes of a transparent mode (TM), an unacknowledged mode (UM),and an acknowledged mode (AM). AM RLC provides error correction throughan automatic repeat request (ARQ).

A radio resource control (RRC) layer is defined only in the controlplane. The RRC layer is responsible for the control of the logicalchannel, the transport channel, and the physical channels in associationwith configuration, reconfiguration, and release of radio bearers. TheRB indicates a logical path provided by a first layer (i.e., PHY layer)and a second layer (i.e., MAC layer, RLC layer, and PDCP layer) for datatransfer between a UE and a network.

Functions of a packet data convergence protocol (PDCP) layer in the userplane include transfer of user plane data, header compression, andciphering. Functions of the PDCP layer in the control plane includetransfer of control plane data and ciphering/integrity protection.

The configuration of the RB indicates a process for specifying a radioprotocol layer and properties of channels to provide a specific serviceand configuring respective detailed parameters and operating methods.The RB may also be divided into a signaling radio bearer (SRB) and adata radio bearer (DRB). The SRB is used as a path for sending an RRCmessage in the control plane, and the DRB is used as a path for sendinguser data in the user plane.

If an RRC connection is established between an RRC layer of the UE andan RRC layer of an E-UTRAN, the UE is in an RRC connected state, andotherwise the UE is in an RRC idle state.

Examples of a downlink transport channel for transmitting data from thenetwork to the UE include a broadcast channel (BCH) for transmittingsystem information and a downlink shared channel (SCH) for transmittinguser traffic or a control message. A traffic or a control message ofdownlink multicast or broadcast service may be transmitted through thedownlink SCH, or may also be transmitted through a separate downlinkmulticast channel (MCH). Examples of an uplink transport channel fortransmitting data from the UE to the network include a random accesschannel (RACH) for transmitting an initial control message and an uplinkshared channel (SCH) for transmitting user traffic or a control message.

Examples of a logical channel which is located above the transportchannel and is mapped to the transport channel include a broadcastcontrol channel (BCCH), a paging control channel (PCCH), a commoncontrol channel (CCCH), and a multicast control channel (MCCH), and amulticast traffic channel (MTCH).

The physical channel includes several OFDM symbols in a time domain andseveral subcarriers in a frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. A resource block, as aresource allocation unit, includes a plurality of OFDM symbols and aplurality of subcarriers. Each subframe may use specific subcarriers ofspecific OFDM symbols (e.g., first OFDM symbol) of a correspondingsubframe for a physical downlink control channel (PDCCH), i.e., an L1/L2control channel A transmission time interval (TTI) is a unit time ofsubframe transmission.

FIG. 3 is a flowchart showing an RRC connection establishment procedureto which the present invention may apply.

A UE sends to a network an RRC connection request message for requestingan RRC connection (S3010). The network sends an RRC connection setupmessage in response to the RRC connection request (S3020). Afterreceiving the RRC connection setup message, the UE enters an RRCconnection mode.

The UE sends to the network an RRC connection setup complete messageused to confirm successful completion of the RRC connectionestablishment (S3030).

FIG. 4 is a flowchart showing an RRC connection reconfigurationprocedure to which the present invention may apply.

An RRC connection reconfiguration is used to modify an RRC connection.This is used to establish/modify/release an RB, to perform a handover,and to set up/modify/release a measurement.

A network sends to a UE an RRC connection reconfiguration message formodifying the RRC connection (S4010). In response to the RRC connectionreconfiguration, the UE sends to the network an RRC connectionreconfiguration complete message used to confirm successful completionof the RRC connection reconfiguration (S4020).

General Carrier Aggregation

A communication environment considered in the embodiments of the presentinvention includes all of multi-carrier support environments.

That is, a multi-carrier system or carrier aggregation (CA) system usedin the present invention refers to a system using an aggregation of oneor more component carriers (CCs) having a bandwidth smaller than atarget band when a target wideband is configured in order to support thewideband.

In the present invention, a multi-carrier means an aggregation ofcarriers (or a carrier aggregation). In this case, an aggregation ofcarriers means both an aggregation between contiguous carriers and anaggregation between non-contiguous carriers.

Furthermore, the number of component carriers aggregated in the downlinkand the number of component carriers aggregated in the uplink may bedifferently configured. A case where the number of downlink componentcarriers (hereafter referred to as a “DL CC”) and the number of uplinkcomponent carriers (hereafter referred to as an “UL CC”) are the same iscalled a symmetric aggregation. A case where the number of DL CCs andthe number of UL CCs are different is called an asymmetric aggregation.Such a carrier aggregation may be interchangeably used with terms, suchas a carrier aggregation, a bandwidth aggregation and a spectrumaggregation.

A carrier aggregation composed of a combination of two or more componentcarriers has a target of supporting a 100 MHz bandwidth in the LTE-Asystem. When one or more carriers having a bandwidth smaller than atarget band are combined, the bandwidth of the combined carrier may belimited to a bandwidth used in the existing system in order to maintainbackward compatibility with the existing IMT system. For example, theexisting 3GPP LTE system supports {1.4, 3, 5, 10, 15, 20} MHzbandwidths, and a 3GPP LTE-advanced system (i.e., LTE-A) may support abandwidth greater than 20 MHz using only the bandwidths forcompatibility with the existing system.

Furthermore, a carrier aggregation system used in the present inventionmay define a new bandwidth regardless of a bandwidth used in theexisting system in order to support a carrier aggregation.

An LTE-A system uses the concept of a cell in order to manage radioresources.

The aforementioned carrier aggregation environment may refer to amulti-cell environment. A cell is defined as a combination of a pair ofa downlink resource (DL CC) and an uplink resource (UL CC), but theuplink resource is not an essential element. Accordingly, a cell mayinclude a downlink resource solely or a downlink resource and an uplinkresource. If a specific UE has only one configured serving cell, it mayhave one DL CC and one UL CC. If a specific UE has two or moreconfigured serving cells, it has DL CCs corresponding to the number ofcells. The number of UL CCs may be equal to or smaller than the numberof DL CCs.

Alternatively, a DL CC and an UL CC may be configured to the contrary.That is, if a specific UE has multiple configured serving cells, acarrier aggregation environment in which the number of UL CCs is greaterthan the number of DL CCs may be supported. That is, a carrieraggregation may be understood as an aggregation of cells having two ormore different carrier frequencies (center frequency of a cell). A“cell” referred in this case needs to be distinguished from a “cell” asa commonly used area covered by a base station.

A cell used in the LTE-A system includes a primary cell (PCell) and asecondary cell (SCell). A P cell and an S cell may be used as a servingcell. In the case of a UE which is in the RRC_CONNECTED state, but inwhich a carrier aggregation has not been configured or which does notsupport a carrier aggregation, only one serving cell including a P cellis present. In contrast, in the case of a UE which is in theRRC_CONNECTED state and in which a carrier aggregation has beenconfigured, one or more serving cells may be present. All of servingcells include a P cell and one or more S cells.

A serving cell (P cell and S cell) may be configured through an RRCparameter. PhysCellId is the physical layer identifier of a cell and hasan integer value from 0 to 503. SCellIndex is a short identifier used toidentify an S cell and has an integer value from 1 to 7. ServCellIndexis a short identifier used to identify a serving cell (P cell or S cell)and has an integer value from 0 to 7. A 0 value is applied to a P cell,and SCellIndex is previously assigned to be applied to an S cell. Thatis, a cell having the smallest ID (or cell index) in ServCellIndexbecomes a P cell.

A P cell means a cell operating on a primary frequency (or primary CC).A P cell may be used by a UE to perform an initial connectionestablishment process or a connection reconfiguration process, and mayrefer to a cell indicated in a handover process. Furthermore, a P cellmeans a cell that is the center of control-related communication amongserving cells configured in a carrier aggregation environment. That is,a UE may receive a PUCCH allocated only in its P cell and performtransmission, and may use a P cell to obtain system information orchange a monitoring procedure. An evolved universal terrestrial radioaccess network (E-UTRAN) may change only a P cell for a handoverprocedure using an RRC connection reconfiguration(RRCConnectionReconfiguration) message including mobility controlinformation (mobilityControlInfo) with respect to a UE supporting acarrier aggregation environment.

An S cell may mean a cell operating on a secondary frequency (orsecondary CC). Only one P cell is allocated to a specific UE, and one ormore S cells may be allocated to a specific UE. An S cell may beconfigured after an RRC connection is established and may be used toprovide an additional radio resource.

A PUCCH is not present in the remaining cells, that is, an S cell,except a P cell of serving cells configured in a carrier aggregationenvironment. An E-UTRAN may provide all of types of system informationrelated to the operation of a cell in the RRC_CONNECTED state through adedicated signal when adding an S cell to a UE supporting a carrieraggregation environment. A change in the system information may becontrolled by the release and addition of a related S cell. In thiscase, an RRC connection reconfiguration (RRCConnectionReconfiguration)message of a higher layer may be used. An E-UTRAN may perform dedicatedsignaling having a different parameter for each UE rather thanbroadcasting within a related S cell.

After an initial security activation process starts, an E-UTRAN mayconfigure a network including one or more S cells by adding them to a Pcell initially configured in a connection configuration process. In acarrier aggregation environment, a P cell and an S cell may operate asrespective component carriers. In the following embodiment, a primarycomponent carrier (PCC) may be used as the same meaning as a P cell, anda secondary component carrier (SCC) may be used as the same meaning asan S cell.

FIGS. 5 and 6 are diagrams showing examples of Layer 2 structures in acarrier aggregation to which the present invention may be applied.

FIG. 5 shows an example of a Layer 2 structure in a carrier aggregationfor the transmission of downlink data, and FIG. 6 shows an example of aLayer 2 structure in a carrier aggregation for the transmission ofuplink data.

Referring to FIGS. 5 and 6, in the case of a carrier aggregation, inorder for one HARQ entity to be required in each serving cell, amulti-carrier of a physical layer is exposed only in a MAC layer.

In the uplink and downlink, if one independent HARQ entity is present ineach serving cell and spatial multiplexing is not present, one transportblock is generated for each TTI in each serving cell. Each transportblock and potential HARQ retransmissions thereof are mapped to a singleserving cell.

FIG. 7 is a diagram showing an example of component carriers and carrieraggregations in a wireless communication system to which the presentinvention may be applied.

FIG. 7(a) shows a single carrier structure used in the LTE system. Acomponent carrier may include a DL CC and an UL CC. One componentcarrier may have a frequency range of 20 MHz.

FIG. 7(b) shows carrier aggregation structured in the LTE_A system. FIG.7(b) shows a case where 3 component carriers, each one having afrequency size of 20 MHz, have been combined. Three DL CCs and three ULCCs are included, but the number of DL CCs and UL CCs is not limited. Inthe case of a carrier aggregation, a UE can monitor three CCs at thesame time, can receive a downlink signal/data, and can transmit anuplink signal/data.

If N DL CCs are managed in a specific cell, a network may allocate M(M≤N) DL CCs to a UE. In this case, the UE may monitor only the Mlimited DL CCs and receive a DL signal. Furthermore, the network mayallocate major DL CCs to the UE by giving priority to L (L≤M≤N) DL CCs.In such a case, the UE must monitor the L DL CCs. Such a method may beidentically applied to uplink transmission.

Linkage between the carrier frequency (or DL CC) of a downlink resourceand the carrier frequency (or UL CC) of an uplink resource may beindicated by a higher layer message, such as an RRC message, or systeminformation. For example, a combination of a DL resource and an ULresource may be configured by linkage defined by a system informationblock Type2 (SIB2). Specifically, the linkage may mean a mappingrelation between a DL CC in which a PDCCH carrying an UL grant istransmitted and an UL CC using the UL grant, and may mean a mappingrelation between a DL CC (or UL CC) in which data for an HARQ istransmitted and an UL CC (or DL CC) in which an HARQ ACK/NACK signal istransmitted.

Dual Connectivity (DC)

FIGS. 8 and 9 illustrate an example of a structure of dual connectivity(DC) and a network interface to which the present invention isapplicable.

In a heterogeneous network supporting small cell evolution, there arevarious requirements related to mobility robustness, increased signalingload due to frequent handover, improvement of per-user throughput,system capacity, etc.

As a solution to realize these requirements, E-UTRAN supports dualconnectivity (DC) operation whereby a multiple RX/TX UEs inRRC_CONNECTED is configured to utilize radio resources provided by twodistinct schedulers, located in two eNBs connected via a non-idealbackhaul over the X2 interface.

The dual connectivity may imply control and data separation. Forexample, control signaling for mobility is provided via a macrocell atthe same time as high-speed data connection is provided via a smallcell.

Further, a separation between downlink and uplink and a connectionbetween the downlink and the uplink are provided via different cells.

eNBs related to dual connectivity for a specific UE may assume twodifferent roles. For example, as shown in FIGS. 8 and 9, one eNB may actas an MeNB or an SeNB.

In the dual connectivity, a UE may be connected to one MeNB and oneSeNB.

The MeNB is an eNB which terminates at least one S1-MME in dualconnectivity, and the SeNB is an eNB providing additional radioresources for the UE, but is not a master eNB in dual connectivity.

In addition, DC with CA configured means an operation mode of the UE inan RRC_CONNECTED state and is configured with a master cell group and asecondary cell group.

Here, “cell group” indicates a group of serving cells associated with amaster eNB (MeNB) or a secondary eNB (SeNB) in dual connectivity.

“Master Cell Group (MCG)” is a group of serving cells associated withthe MeNB and includes a primary cell (PCell) and optionally one or moresecondary cells (SCells) in dual connectivity.

“Secondary Cell Group (SCG)” indicates a group of serving cellsassociated with a SeNB including primary SCell (pSCell) and optionallyone or more SCells.

Here, “cell” described below should be distinguished from a ‘cell’ as ageneral region covered by an eNB. That is, the cell indicates acombination of downlink and optionally uplink resources.

The linking between a carrier frequency (e.g., center frequency of thecell) of downlink resources and a carrier frequency of uplink resourcesis indicated in system information transmitted on the downlinkresources.

MCG bearer is radio protocols located only in the MeNB to use only MeNBresources in dual connectivity, and SCG bearer is radio protocolslocated only in the SeNB to use SeNB resources in dual connectivity.

Split bearer is radio protocols located in both the MeNB and the SeNB touse both MeNB resources and SeNB resources in dual connectivity.

As requirements for supporting various real-time application servicesincrease, future communication technologies such as 5G are aiming atconstructing ultra-low latency systems with an extremely short responsetime to meet various requirements.

Because services requiring the ultra-low latency consider a scenariorequiring both a latency and high reliability data transmission, thereis a need for a technology (ultra-reliable and low latency communication(URLLC)) that allows data to be transmitted quickly at high reliability(about 99.999%).

The low latency high reliability services require high reliability bytransmitting a data packet in a short TTI. As a method for satisfyingthe high reliability, there is a transmission through a time diversityscheme and a transmission through a frequency diversity scheme.

The time diversity scheme means a scheme capable of securing goodtransmission quality by combining again reception data transmitted froma reception side if a transmission side transmits the same data severaltimes at a time interval on a time axis.

The frequency diversity scheme means a scheme capable of preventingfading by selecting good reception data or combining different datausing different reception properties at each frequency if a transmissionside transmits the same data at several frequencies on a frequency axis.

Because the low latency high reliability services transmit data in ashort TTI, it is difficult to obtain a gain using the time diversityscheme among the two schemes. Thus, if different frequencies of theabove-mentioned multi-cell/different carrier are used for datatransmission, a gain of the frequency diversity can be obtained.

Because the low latency high reliability services transmit the datapacket in the short TTI, a large amount of bandwidth may be required. Inthis instance, since it is possible to transmit data to different cellsin dual connectivity (DC) that is a multi-cell utilization technologydescribed above, a wider bandwidth can be used.

Further, if a multi-carrier utilization technology, a carrieraggregation (CA) technology, is used, a wider bandwidth can be obtainedbecause several component carriers (CCs) are used.

However, in an existing system, because the DC and CA technologies havebeen implemented for the purpose of improving the throughput of the UEor traffic offloading, they are not suitable for the low latency highreliability services. Thus, in a future communication system, the DC andCA technologies should be designed to increase data reliability as wellas data throughput.

Further, the current DC and CA technologies have a problem that a methodfor duplicating and configuring a unit of transmission so as to transmitthe same data via multi-cell/multi-carrier is not supported.

Accordingly, in order to solve the problem, the present inventionproposes a method for duplicating corresponding data and transmittingand receiving the duplicate data so that the same data is redundantlytransmitted and received via the multi-cell/different carrier.

Hereinafter, the present invention assumes that Layer 2 of a UE or abase station includes N sublayers.

In the present invention, when uplink data is transmitted and received,the UE may be called a transmitting device, and the base station may becalled a receiving device. When downlink data is transmitted andreceived, the UE may be called a receiving device, and the base stationmay be called a transmitting device.

FIG. 10 is a flow chart illustrating an example of a method fortransmitting the same data proposed by the present specification.

Referring to FIG. 10, when transmission of multiple duplicate data viamulti-cell/multi-carrier is activated, a UE or a base station mayreplicate one data, generate multiple same data, and transmit thegenerated multiple same data via the multi-cell or the multi-carrier.

Hereinafter, a function of transmitting multiple same data viamulti-cell or different carrier is referred to as duplicated data TX.

More specifically, the UE and the base station may configure orreconfigure a plurality of logical paths for transmitting and receivingmultiple same data in a process for configuring or reconfiguring aninitial logical path (e.g., data radio bearer (DRB)) and may allocate aspecific logical path identifier (e.g., DRB identifier (ID)) to each ofthe plurality of configured logical paths in S10010.

The base station transmits system information including the allocatedspecific logical path identifiers to the UE.

The UE may recognize logical paths capable of transmitting the multiplesame data through the specific logical path identifiers transmitted fromthe base station and may transmit and receive the multiple same datathrough the corresponding logical paths.

Alternatively, in a process for configuring an initial logical pathbetween the UE and the base station, the base station transmits, to theUE, an indication message including an indication indicating a logicalpath configured for the transmission of multiple same data.

The UE may recognize whether or not a logical path configured via thetransmitted indication message is the logical path configured for thetransmission of the same data and may transmit and receive multiple samedata through corresponding logical paths if the configured logical pathis the logical path configured for the transmission of the same data.

As another example, the base station may inform the UE of whether or nota logical path configured via an RRC message is the logical pathconfigured for the transmission of multiple same data.

For example, the base station transmits, to the UE, an RRC messageincluding an indication indicating the logical path configured for thetransmission of multiple same data.

The UE may recognize whether or not a logical path configured via thetransmitted RRC message is the logical path configured for thetransmission of the same data and may transmit and receive multiple samedata through corresponding logical paths if the configured logical pathis the logical path configured for the transmission of the same data.

Next, when data for providing a specific service (e.g., URLLC service,etc.) requiring high reliability and low latency is generated, the UE orthe base station (hereinafter, the transmitting device) generatesmultiple same data in S10020.

For example, when data (e.g., TCP/IP packet) for providing a specificservice requiring the URLLC described above is generated, a thirdsublayer (e.g., a PDCP layer of a 3GPP LTE/LTE-A system) of Layer 2 ofthe transmitting device duplicates (or replicates) data, which isgenerated as many as the number of configured logical paths or thenumber of multi-cell/multi-carrier associated with (or corresponding to)the configured logical paths, and delivers the duplicated data to asecond sublayer (e.g., an RLC layer of the 3GPP LTE/LTE-A system) of theLayer 2 that is a lower layer.

More specifically, the third sublayer receives data from a specificlayer (e.g., TCP/IP layer) through a logical path configured for eachTTI and stores the received data in a buffer (a first buffer) of thethird sublayer. In this instance, the buffer of the third sublayer ispresent for each configured logical path.

For example, the buffer of the third sublayer may be present as follows.

-   -   Data 1 from eMBB (enhanced mobile broadband) DRB that will not        apply duplicated data TX    -   Data 2 from URLLC DRB that will apply duplicated data TX

In this instance, the eMBB DRB and the URLLC DRB indicate a logical pathfor providing eMBB services and a logical path for providing URLLCservices, respectively.

The third sublayer duplicates (or replicates) data, which will apply theduplicated data TX among data stored in the buffer, as many as thenumber of configured logical paths or the number ofmulti-cell/multi-carrier.

More specifically, the third sublayer performs a header compressionfunction (e.g. Robust Header Compression (ROHC) function in PDCP layer)reducing a header size of data that is relatively large in size andcontains unnecessary control information, in order to efficientlytransmit data stored in the buffer via a radio interface.

Further, the third sublayer performs a ciphering function (e.g.ciphering function in PDCP layer) for security of original data usingciphering keystream, etc., so that a third device other than thetransmitting device and the receiving device does not recover date.

The third sublayer duplicates data transmitted through a logical path,which will apply the duplicated data TX, as many as the number ofmulti-cell/multi-carrier. Namely, the third sublayer duplicates (orreplicates) data (a first data) for providing a specific service as manyas the number of configured logical paths or the number ofmulti-cell/multi-carrier and generates multiple same data.

Next, the third sublayer delivers the generated multiple same data tothe second sublayer.

In this instance, when multiple same data is redundantly transmitted viamulti-cell, a portion of the multiple same data may be transmitted to asecond sublayer of another transmitting device via a specific interfaceprotocol connecting between transmitting devices for the redundanttransmission.

Each second sublayer reconfigures each of multiple same data transmittedfrom the third sublayer according to radio resources of the allocatedlower layer through a segmentation and concatenation function.

In this instance, the second sublayer may exist as many as the number ofmultiple same data, and each second sublayer may reconfigure each ofmultiple same data.

More specifically, the second sublayer receives data from the thirdsublayer through a plurality of logical paths configured for each TTIand stores the received data in a buffer (a second buffer) of the secondsublayer. In this instance, the buffer of the second sublayer may bepresent for each configured DRB.

For example, the buffer of the second sublayer may be present asfollows.

-   -   Data 1 in eMBB (enhanced mobile broadband) DRB second sublayer        transmission buffer    -   Data 2 in URLLC DRB second sublayer transmission buffer    -   Duplicated data from data 2 in URLLC DRB second sublayer        transmission buffer

Next, the second sublayer segments and/or concatenate data stored ineach buffer of the second sublayer according to an allocated amount ofradio resources of Layer 1 (e.g., a PHY layer).

In this instance, the allocated amount of radio resources may bedetermined depending on radio conditions, a transmission power,transmission resources, quality of service (QoS) of a logical path, andthe like.

Each second sublayer delivers reconfigured data to a first sublayer(e.g., an MAC layer) of the Layer 2 that is the lower layer.

The first sublayer multiplexes multiple datas received from a pluralityof second sublayers and delivers the multiplexed multiple datas to theLayer 1.

More specifically, the first sublayer receives and multiplexes multiplesame data for providing a specific service from the second sublayer ineach TTI and transmits the multiplexed multiple same data on a cell (ora component carrier) corresponding to each logical path in S10030.

There may exist the following three methods for multiplexing data by thefirst sublayer.

Firstly, the first sublayer may multiplex datas of different servicestransmitted through different logical paths into one data and transmitthe multiplexed one data on the same cell (or a component carrier)corresponding to a logical path.

Secondly, the first sublayer may multiplex each of multiple datas ofdifferent services transmitted through different logical paths andtransmit the multiplexed multiple data on the same cell (or componentcarrier) corresponding to a logical path.

In this case, data of a specific service (e.g. URLLC service requiringhigh reliability and low latency) can be preferentially transmittedaccording to a priority of a logical path.

Alternatively, when a priority of a specific logical path is configuredas infinity, data of other services in the same cell is not transmitted,and only data of a specific service may be transmitted through thelogical path whose the priority is configured as infinity.

Thirdly, the first sublayer may multiplex each of datas of differentservices transmitted through different logical paths and transmit themultiplexed datas on different cells (or component carriers)corresponding to a logical path. In this case, the different cells maybe different subbands (or component carriers) of the same cell.

Next, when the transmitting device receives a response messageindicating successful reception of multiple same data from the receivingdevice, the transmitting device can stop the transmission of themultiple same data in S10040.

More specifically, when one of second sublayers of the receiving devicesuccessfully receives one of multiple same data, a third sublayer of thetransmitting device transmits an indication to a second sublayer of thetransmitting device and informs the second sublayer of a stop of thetransmission (or retransmission) of the multiple same data.

In this instance, the third sublayer may inform the second sublayer ofthe transmission stop of multiple same data through the followingmethods.

-   -   In case of the transmission of downlink data using multi-cell,        an indication indicating the transmission stop may be        transmitted as a control message via a specific interface (e.g.,        Xd interface) between the base stations.    -   In case of the transmission of downlink data using multi-carrier        or the transmission of uplink data using        multi-cell/multi-carrier, an indication indicating the        transmission stop may be delivered from a third sublayer to a        second sublayer through an internal operation of the        transmitting device.    -   In the case where a third sublayer and a second sublayer are        physically connected, an indication indicating a transmission        stop may be delivered from the third sublayer to the second        sublayer through an internal operation of the transmitting        device.    -   In the case where a third sublayer and a second sublayer are not        physically connected, an indication indicating a transmission        stop may be transmitted as a control message via a specific        interface (e.g., Xd interface) between the base stations.

The second sublayer, that receives an indication indicating atransmission stop from the third sublayer, stops the transmission and/orthe retransmission of data stored in a buffer according to a specificmode.

For example, the second sublayer in a transparent mode or anunacknowledged mode stops the transmission of data stored in the buffer,and the second sublayer in an acknowledged mode stops both thetransmission and the retransmission of data stored in the buffer.

Through the above-described method, the transmitting device duplicatesdata of a specific service and redundantly transmits multiple same data,thereby satisfying requirements of a specific service, in particular,services requiring high reliability and low latency.

FIGS. 11 to 13 illustrate an example of a multiplexing method fortransmitting the same data proposed by the present specification.

FIGS. 11 to 13 illustrate in detail a method for multiplexing data in atransmitting device described in FIG. 10.

As shown in FIGS. 11 to 13, a second sublayer for reconfiguring data forproviding services may exist as many as the number of data or the numberof configured logical paths, and datas reconfigured by the secondsublayer are multiplexed by a first sublayer.

FIG. 11 illustrates an example of a method for multiplexing datas ofdifferent services transmitted through different logical paths into onedata and transmitting the multiplexed one data on the same cell (orcomponent carrier) corresponding to a logical path.

Referring to FIG. 11, data of eMBB service and data of URLLC servicetransmitted through different logical paths are multiplexed into onedata and then are transmitted on the same cell.

In FIG. 11, (a) illustrates an example of a case of redundantlytransmitting multiple same data via multi-cell, and (b) illustrates anexample of a case of redundantly transmitting the same data viadifferent component carriers of the same cell.

As shown in (a) of FIG. 11, the same data replicated for providing URLLCservice is transmitted to another base station via a specific networkinterface.

The transmitted same data is multiplexed and is transmitted on acomponent carrier CC2 corresponding to a logical path.

As shown in (b) of FIG. 11, when the same data is redundantlytransmitted via different component carriers of the same cell,duplicated data is multiplexed on the same cell and is transmitted on acomponent carrier CC2 corresponding to a logical path.

FIG. 12 illustrates an example of a method for multiplexing each ofdatas of different services transmitted through different logical pathsand transmitting the multiplexed multiple datas on the same cell (orcomponent carrier) corresponding to a logical path.

Referring to FIG. 12, data of eMBB service and data of URLLC servicetransmitted through different logical paths each are multiplexed andthen are transmitted on the same cell. In this instance, data of theURLLC service requiring high reliability and low latency can bepreferentially transmitted.

Further, when a priority of a logical path configured for providing theURLLC service is configured as infinity, eNB 1 can transmit only datafor providing the URLLC service on a component carrier CC1.

In FIG. 12, (a) illustrates an example of a case of redundantlytransmitting multiple same data via multi-cell, and (b) illustrates anexample of a case of redundantly transmitting the same data viadifferent component carriers of the same cell.

As shown in (a) of FIG. 12, the same data replicated for providing URLLCservice is transmitted to another base station via a specific networkinterface.

The transmitted same data is multiplexed and is transmitted on acomponent carrier CC3 corresponding to a logical path.

As shown in (b) of FIG. 12, when the same data is redundantlytransmitted via different component carriers of the same cell,duplicated data is multiplexed on the same cell and is transmitted on acomponent carrier CC2 corresponding to a logical path.

FIG. 13 illustrates an example of a method for multiplexing each ofdatas of different services transmitted through different logical pathsand transmitting the multiplexed datas on different cells (or componentcarriers) corresponding to a logical path.

Referring to FIG. 13, data of eMBB service and data of URLLC servicetransmitted through different logical paths each are multiplexed andthen are transmitted on different cells or different subbands of thesame cell.

In FIG. 13, (a) illustrates an example of a case of redundantlytransmitting multiple same data via multi-cell, and (b) illustrates anexample of a case of redundantly transmitting the same data viadifferent component carriers of the same cell.

As shown in (a) of FIG. 13, the same data duplicated for providing URLLCservice is transmitted to another base station via a specific networkinterface.

The transmitted same data is multiplexed and is transmitted on acomponent carrier CC3 corresponding to a logical path.

As shown in (b) of FIG. 13, when the same data is redundantlytransmitted via different component carriers of the same cell,duplicated data is multiplexed on the same cell and is transmitted on acomponent carrier CC3 corresponding to a logical path.

FIGS. 14 and 15 illustrate an example of a method and a de-multiplexingmethod for receiving and processing the same data proposed by thepresent specification.

Referring to FIGS. 14 and 15, when transmission of multiple duplicatedata via multi-cell/multi-carrier is activated, a UE or a base stationmay receive and recover multiple same data via multi-cell ormulti-carrier.

More specifically, a receiving device (the UE or the base station) mayreceive multiple same data from a transmitting device in S14010. In thisinstance, the multiple same data is transmitted on one or more cells orcomponent carriers corresponding to a logical path configured fortransmitting the multiple same data.

A first sublayer of Layer 2 of the receiving device de-multiplexes thetransmitted multiple same data in S14020 and delivers the de-multiplexedmultiple same data to a second sublayer.

More specifically, the first sublayer receives multiple same datatransmitted on multi-cell/multi-carrier in each TTI and performs thede-multiplexing of the multiple same data.

There may exist the following three methods of the de-multiplexing.

Firstly, when datas of different services transmitted through differentlogical paths are multiplexed into one data and are transmitted on thesame cell, the first sublayer de-multiplexes the transmitted data, mapsthe de-multiplexed data to a logical path configured for providing eachservice, and delivers the mapped data to the second sublayer.

For example, as shown in (a) of FIG. 15, data transmitted on a componentcarrier 1 CC1 is de-multiplexed.

Data for providing eMBB service among de-multiplexed datas is mapped toa logical path for providing the eMBB service and is delivered to thesecond sublayer. Further, data for providing URLLC service among thede-multiplexed datas is mapped to a logical path for providing the URLLCservice and is delivered to the second sublayer.

Data transmitted on a component carrier 3 CC3 is de-multiplexed, ismapped to a logical path for providing the URLLC service, and isdelivered to the second sublayer.

Secondly, when datas of different services transmitted through differentlogical paths each are multiplexed and are transmitted on the same cell,the first sublayer de-multiplexes the transmitted data, maps thede-multiplexed data to a logical path configured for providing eachservice, and delivers the mapped data to the second sublayer.

For example, as shown in (b) of FIG. 15, data transmitted on a componentcarrier 1 CC1 is de-multiplexed, is mapped to a logical path forproviding the URLLC service, and is delivered to the second sublayer.

Further, data transmitted on a component carrier 3 CC3 isde-multiplexed, is mapped to a logical path for providing the URLLCservice, and is delivered to the second sublayer.

In this instance, because a priority of the logical path for providingthe URLLC service is higher than a priority of the logical path forproviding the eMBB service, data providing the URLLC service via thecomponent carrier 1 CC1 is transmitted earlier.

Thirdly, when datas of different services transmitted through differentlogical paths each are multiplexed and are transmitted on differentcells, the first sublayer de-multiplexes the transmitted data, maps thede-multiplexed data to a logical path configured for providing eachservice, and delivers the mapped data to the second sublayer.

For example, as shown in (c) of FIG. 15, data transmitted on eachcomponent carrier or on a subband of each component carrier isde-multiplexed, and data for providing each service is mapped to alogical path for providing URLLC service and is delivered to the secondsublayer.

The second sublayer receives the de-multiplexed data from the firstsublayer and performs a radio link control function in S14030.

Namely, the second sublayer receives de-multiplexed data includingmultiple same data from the first sublayer through a logical pathconfigured for providing each service in each TTI and performs a radiolink control function.

For example, the second sublayer performs a function of HARQ reorderingand a reassembly function of segmented or concatenated datas. Further,the second sublayer may decide whether there is a loss of data receivedaccording to the configuration and may perform an ARQ function for datarecovery.

Next, the second sublayer delivers multiple same data to the thirdsublayer.

The third sublayer performs a recovery of the received multiple samedata in S14040.

More specifically, the third sublayer receives each of multiple samedata through each logical path configured for each TTI and stores thedata in a reception buffer. In this instance, the reception buffer ispresent only in one logical path connected to a TCP/IP layer regardlessof the number of logical paths for the transmission of multiple samedata.

Further, the reception buffer is present for each of logical paths notsupporting multiple same data.

The third sublayer performs functions of discarding received data,informing of a transmission stop of multiple same data, or waiting forthe reception of multiple same data transmitted in a next TTI, etc.depending on whether or not the multiple same data is received.

More specifically, when the third sublayer successfully receives all ofdata transmitted on a cell or a component carrier corresponding to alogical path configured for the transmission of multiple same data, thethird sublayer discards remaining same data excluding one data from themultiple same data.

When the third sublayer receives at least one data of multiple samedata, the third sublayer informs the second sublayer of a reception stopof data through an indication indicating a reception stop of multiplesame data.

In this instance, the third sublayer may inform the second sublayer of areception stop of multiple same data through the following methods.

-   -   In case of the transmission of uplink data using multi-cell, an        indication indicating a transmission stop may be transmitted as        a control message via a specific interface (e.g., Xd interface)        between the base stations.    -   In case of the transmission of uplink data using multi-carrier        or the transmission of downlink data using        multi-cell/multi-carrier, an indication indicating a reception        stop may be delivered from a third sublayer to a second sublayer        through an internal operation of the transmitting device.    -   In the case where a third sublayer and a second sublayer are        physically connected, an indication indicating a reception stop        may be delivered from the third sublayer to the second sublayer        through an internal operation of the transmitting device.    -   In the case where a third sublayer and a second sublayer are not        physically connected, an indication indicating a reception stop        may be transmitted as a control message via a specific interface        (e.g., Xd interface) between the base stations.

When the third sublayer fails to receive all of multiple same data, thethird sublayer waits for the reception of multiple same data transmittedin a next TTI.

Next, the third sublayer transmits recovered data to an upper layerthrough a corresponding logical path.

The present invention can receive multiple same data for providing aspecific service through the above-described method and can efficientlyrecover data by performing a specific operation depending on whether allor part of the multiple same data has been received.

FIG. 16 illustrates an example of an internal block diagram of awireless device to which the present invention is applicable.

Here, the wireless device may be a base station and a UE, and the basestation includes both a macro base station and a small base station.

As shown in FIG. 16, a base station 1610 and a UE 1620 includecommunication units (transmission/reception units or RF units) 1613 and1623, processors 1611 and 1621, and memories 1612 and 1622,respectively.

In addition, the base station and the UE may further include an inputunit and an output unit.

The communication units 1613 and 1623, the processors 1611 and 1621, theinput units, the output units, and the memories 1612 and 1622 arefunctionally connected to perform a method proposed by the presentspecification.

If the communication units (transmission/reception units or RF units)1613 and 1623 receive information made from physical layer protocol,they transfer the received information to a radio frequency (RF)spectrum, perform filtering, amplification, etc. of the information, andtransmit the information to an antenna. Further, the communication unitstransfer a RF signal received from the antenna to a band that can beprocessed in the physical layer protocol, and function to perform thefiltering.

The communication unit may also include a switch function for switchingbetween the transmission and reception functions.

The processors 1611 and 1621 implement functions, processes and/ormethods proposed by the present specification. Layers of radio interfaceprotocol may be implemented by the processor.

The processor may be represented by a controller, a control unit, acomputer, and the like.

The memories 1612 and 1622 are connected to the processors and store aprotocol or a parameter for performing an uplink resource allocationmethod.

The processors 1611 and 1621 may include an application-specificintegrated circuit (ASIC), other chip set, a logic circuit, and/or adata processing device. The memory may include a read-only memory (ROM),a random access memory (RAM), a flash memory, a memory card, a storagemedium, and/or other storage devices. The communication unit may includea baseband circuit for processing a radio signal. When embodiments areimplemented in software, the above-described method can be implementedby a module (process, function, etc.) performing the above-describedfunctions.

The module is stored in the memory and can be executed by the processor.The memory may be inside or outside the processor and may be connectedto the processor by various well known means.

The output unit (a display or a display unit) is controlled by theprocessor and outputs information output from the processor togetherwith a key input signal generated in a key input unit and variousinformation signals from the processor.

Furthermore, although the respective figures have been dividedlyillustrated for convenience of explanation, it can be designed thatembodiments described in the respective figures are combined toimplement a new embodiment. It is also within the scope of the presentinvention to design a computer readable recording medium, in which aprogram for executing the previously described embodiments is recorded,according to the needs of those skilled in the art.

A direction-based device search method according to the presentspecification is not limitedly applied to the configurations and themethods of the embodiments described above, but may be implemented byselectively combining all or some of the respective embodiments so thatvarious modifications of the embodiments can be made.

The direction-based device search method according to the presentspecification can be implemented as a processor-readable code on aprocessor-readable recording medium included in a network device. Theprocessor-readable recording medium includes all kinds of recordingdevices for storing data which can be read by a processor. Examples ofthe processor-readable recording medium include ROM, RAM, CD-ROM, amagnetic tape, a floppy disk, and an optical data storage device, andthe processor-readable recording medium also includes a deviceimplemented in the form of a carrier wave, for example, transmissionover Internet. In addition, the processor-readable recording medium maybe distributed to computer systems connected over a network, and theprocessor-readable code may be stored and executed in a distributedmanner.

Although the preferred embodiments of the present specification havebeen illustrated and described with reference to a number ofillustrative embodiments thereof, numerous other modifications andembodiments may be devised by those skilled in the art that will fallwithin the scope of the principles of this specification. Themodifications should not be individually interpreted from the technicalspirit or the prospect of the present invention.

The present specification has described both the article invention andthe method invention and may complementally apply the descriptions ofthe two inventions, if necessary.

INDUSTRIAL APPLICABILITY

Although a RRC connection method in a wireless communication systemaccording to the present invention has been described with reference toexamples applied to a 3GPP LTE/LTE-A system, it is also applicable tovarious wireless communication systems other than the 3GPP LTE/LTE-Asystem.

The invention claimed is:
 1. A method of transmitting, by a transmittingdevice, data to a receiving device in a wireless communication system,the method comprising: generating at least one duplicate data usingspecific data at a first layer of a layer 2 of the transmitting devicebased on generating the specific data related to a specific service;transmitting, to the receiving device, the specific data and the atleast one duplicate data on at least of a plurality of cells or aplurality of carriers associated with the plurality of radio bearers;and based on receiving, from the receiving device, an Acknowledgement(ACK) indicating a reception success of the specific data or the atleast one duplicate data, instructing stop of transmission of thespecific data and the at least one duplicate data from the first layerto a second layer of the layer 2, wherein, for the plurality of radiobearers, a transmission of duplicate data is indicated by a beareridentifier.
 2. The method of claim 1, wherein the first layer performs aheader compression function.
 3. The method of claim 1, wherein thespecific data and the at least one duplicate data are reconfigured bythe second layer.
 4. The method of claim 1, further comprising:delivering the specific data from a TCP/IP layer of the transmittingdevice to the first layer; and storing the specific data in a firsttransmission buffer of the first layer.
 5. The method of claim 1,wherein a number of the second layers is equal to a number of thespecific data and the at least one duplicate data.
 6. The method ofclaim 5, wherein the specific data and the at least one duplicate dataare reconfigured through a segmentation and concatenation function basedon an allocated resource.
 7. The method of claim 6, wherein theallocated resource is determined by radio conditions, a transmissionpower, a transmission resource, or quality of service (QoS) of each ofthe plurality of radio bearers.
 8. A method of receiving, by a receivingdevice, data from a transmitting device in a wireless communicationsystem, the method comprising: receiving, from the transmitting device,specific data and at least one duplicate data on at least of a pluralityof cells or a plurality of carriers associated with a plurality of radiobearers; delivering the specific data and the at least one duplicatedata from a first layer of a layer 2 of the receiving device to a secondlayer of the layer 2 of the receiving device; storing one data among thespecific data and the at least one duplicate data in a reception bufferof the second layer; discarding remaining data excluding the one datafrom the specific data and the at least one duplicate data; instructingstop of transmission of data duplicated with the one data from thesecond layer to the first layer; and transmitting, to the transmittingdevice an Acknowledgement (ACK) indicating a reception success of thespecific data or the at least one duplicate data.
 9. The method of claim8, further comprising performing a radio link control function based onthe specific data and the at least one duplicate data through the firstlayer, wherein the radio link control function is one of a hybridautomatic repeat request (HARQ) function, a reassembly function ofsegmented or concatenated data, or a recovery function of lost data. 10.The method of claim 9, further comprising: recovering the one datathrough the second layer; and delivering the recovered one data to aTCP/IP layer.
 11. A transmitting device for transmitting data to areceiving device in a wireless communication system, the transmittingdevice comprising: at least one transceiver configured to transmit andreceive a radio signal with an outside; and at least one processorfunctionally coupled to the at least one transceiver, wherein the atleast one processor is configured to: generate at least one duplicatedata using specific data at a first layer of a layer 2 of thetransmitting device based on generating the specific data related to aspecific service; transmit, to the receiving device, the specific dataand the at least one duplicate data on at least of a plurality of cellsor a plurality of carriers associated with the plurality of radiobearers; and based on receiving, from the receiving device, anAcknowledgement (ACK) indicating a reception success of the specificdata or the at least one duplicate data, instruct stop of transmissionof the specific data and the at least one duplicate data from the firstlayer to a second layer of the layer 2, wherein, for the plurality ofradio bearers, a transmission of duplicate data is indicated by a beareridentifier.